Telegraph system



Jan. 26, w T REA TELEGRAPH SYSTEM Filed April 23. 193].

INVENTOR ATTORNEY Patented Jan. 26, 1932 www STATES PATENT orricr: f

WILTON T. NEA, or nLnsHrNcr, NEW YORK, AssreNOR 'ro AMERICAN `TELEPHONEAND y 'rnrnsnnrn cOMPANmA- CORPORATION or Nnw YORK TELEGRAPH SYSTEMApplication led April 23,

This invention relates to telegraph systems and, particularly, tobreaking arrangements for'such systems. y In'telegraph systems" suchals" duplex systems, it is often desirable for an Operator at onestation `to break7 in on the line or to interrupt the operator who maybe sending from a distant station in order to obtain Control of thecircuit. `It is, in general, the

104 object of this invention to provide improved arrangements `for thispurpose by providing at a telegraphl` station arrangements whereby thereceivingrelay is maintained continuously in the marking conditionwhenever the 15, sending relay is in the spacing condition, thusrendering the incoming signals to the.. re-

ceiving relay inetectual` to the localcircuit and allowinga-spacing'signal to be sentto the sending operator, the spacing signalcausing like `battery polarities tobe connected to both ends of theloopcircuit and vinterrupting the sending.

The breaking `feature of the telegraph system is generally accomplishedby a break relay which forms equipment furnished inaddition to thesending and receiving relays of the telegraph repeater. Another objectof this invention is to do away with this additional equipment, i. e.,the break relay,

. and to "accomplish the purpose voi? such a relay by means of thesending and receiving relay circuits. f

While this invention "will be pointed out with particularityin theappended claims, the inventionitself, both as to its Jfurther objectsand features, will ber better understood from the detailed descriptionhereinafter following whenread in connection with the accompanyingdrawingr which shows oneI embodiment of the invention given merely forthe purpose of illustration.

\ lIn the drawing there is shown one terminal oi'4 a carrier telegraphchannel at which there is a line L1 over which signals coming in from adistant station `may be received and a line L5 over whichsignals may betransmitted to a distant station. The pulses of carrier current incomingover line L1 flow through a. 5 receivingfilter F1 and an amplifier A andare t rectified' by a detector tube V; It will be 1931. serial No.532,362.

apparent that pulses Vofdirect current oorresponding to the receivedpulses of alternating current will appear inthe plate circuit Ofdetector tube V, in which are included the main` winding W2 of a polarreceivingzrelay R1 and the primary winding W1" of a kick transformer T2.

Each pulse of direct current flowing through the winding W2 tends tomove `the armature of the receiving relay R1 to its marking contact M.lWhen ground is applied to the movable contact P1 of the key K1, eitherthrough the fixed Contact P2 or through the fixed contact P5 `and thearmatureand marking Contact M of the sending relay' R2, current lowsfrom the batteryv B3 through the winding W2 over the'resistance Z2 toground, current also iiowing from battery B2 through the winding W5 overthe resistance Z2 toground. The current in the winding W5 tends to movethe armature toward the marking contact M with a force equal to halfthat produced by the winding W2. The current in the Winding W5 tends tomove'the armature toward the 'spacing contact S with a force equal butopposite to that producedby winding W2. Itis thus apparent that thecombined effect of windings fr and W5 tends to movethe armature, towardthe spacing contact S Witha forcev equal to one-half the force which thecurrent in winding W2 exerts toward the marking contact M. It will beseen, therefore, that with normal current flowing through thewinding W5,the armature of the receiving relay R1 will move back and forth bewteenthe marking contact M and the spacing contact S in accordance with thertelegraph signals impressed upon the winding W2 The eiect of winding W3is merely to accelerate the motion of the armature. The rise and decayof current flowing through the winding Vl of the kick transformer T2induces in its winding W5 currents which, flowing through the windingW5, aid the signalingcurrents in moving the armature.

For half-duplex operation the key K1 is operated, thereby connecting thecontact P1 P4 and disconnecting contacts P7 and P2.`

In this case the armature of the receiving relay R1 is connected to thelocal loop circuit L2, which includes the winding N7 and T8 of a polarsending relay R2, a key K2, a sounder N1, a battery B2 and theresistances Z5 and Z6. The batteries B2, B7i and B7 are of susbtantiallyequal voltages and in fact they may be the same battery. `With key K2closed, as will normally be the case when the local operator isreceivingsignals and when the armature of the receivingrelay R1 is on its markingcontact M, current will flow from the battery B.i through the sounderN1', the' key K2, the resistance Zandthe Winding `W7, to the battery B6and current will'iiow from ground` through the resistance Z6k and, theWinding. W2 vto *the battery- B6. Thecurrent through-winding vlsmilltend to movethe armature of the sending relay R2 to its-.spacing fcontactl S andv the current through wind'- ingjVV'7.` will tend.- tomove s-aid.ar1natureto its marking Contact M with tWicethe'orce extertedby windingA WS. /Vhenthef armature ofthereceivingrelay R1is--onits-spacing contact S, currentwill flow from the-battery B7through; the winding VS andI the resistance-Z2 to ground. 'llhiscurrent4will tend to move thearmaturero--thesending relay B2j to its; marking?contact M1. No current will; liowthrough the; circuit including4 theWinding/V7,.the resistance Z5, .the key K2 and the 'sounder N1,Ysincebatteries-B7 and-.Bgk are mutually.. opposed., It Willthusbe-apparent thaty asthe armature of thereceiving relay R51` alternatesbetween itsv marking; and, spacing contacts-.in,accordance with lreceived/telegraph signals-,pulses of current will flow through thesounder Nhoperating iti. in .accordance with said-signals.v However,itis to be noted that'- the operationofthe armature ofthe receiving:relay will not' operate the sendingrelay R2 when.the key K2 is closedsince the -winding'VV7 and NVS are then-in balancecl-.relationwith;respect to the armature of the receiving relay R7 vWhen the armature ofvthe receiving, relay R2v is` at rest. ony its mar-king'contact M, aswill normally bethe case whentheoper'- ator. at the localstation.is-transmitting signals, current from-the batteries B12 and B6whichare serially-aiding, will flow through the windinglVT of thesendingfrelay R2. As stated ,here-inbefore, Vthis current Willtend tomovefthe-armature-of said relay to its-mark- "i" ing contact M. Currentwill iiow from the battery-BG vthrough the winding, W2 and theresistance ZG to ground, and this-current will tendftounove the armatureof the-sending relay B2 to its.- spacing Contact Sl with half the forceexerted.byfthecurrent through the winding 77. It will be apparent thatthe operation ofthekey- K2 willfinterrupt the current:throughtheuwindingfvlh and will i causev the'armature o-ffthe sendingVrelay R2 to alternate between `its-1narki'ng and spacing contacts inaccordance With the telegraph signals sent by the key K2. Said armaturewill alternately open and close a short circuit across the output of thealternating current generator G and will thus cause pulses ofalternating current corresponding to said telegraphsignals to flowthrough the sending iilter F2 and over the line L3 to the distantstation. The operation of the sending relay armature alsoalternately'connects to ground and disconnects from ground the circuitwhich includes the neutral sounder N2, the resistance Z7 and the batteryB5, which is of the samevoltage and polarity as the battery B3 and'may,in fact, be the same battery. A resistance Z2.may, if desired, beuse'd'to shunt the sounder i i2. The sounder N2 is caused to operate in4accordance with the transmitted signals, as .described hereinabove. thevrepeater station and its purpose is to allow the repeater attendant to.readthe outgoing signals.

Thevcurrent through the winding W5 oi the receiving relay R1 will now bedependent upon the positionof the armature of the sending relay R2, thiscurrent being`v substantiallyv Zerowhen. saidf armature is not`connectedto its-- marking contact-7M. Hence, it

will beapparent that when the armature of the sending relay R2yis-onitsi spacing-,contact S,,the current through the winding-*W2 willcause the armature of the receiving-relay R1 to remain-on its marking.contact. M irrespective of; the pulses ot current. lowing thru Winding72. If this were not. so, i. e., if the operation of receiving relay R1Were independent of the position of the armature' ot the sending relay.R2 and if the operator should open'the key-K2 to breakthe distantoperator while signals were being received by relay Rhitf would be seenthat the sending relayfR1 might be operated by these incomingfsignals,as reversalsof. current would How from the armature of the' receivingrelay through the winding l/VS of the sending relay R2 to ground and thecurrent through the winding W7 would be substantially` zero. This-mightcause a retransmission of signals back to the sending operator over theline L5, for a periody of time dependent upon the length of thefcircuit.In otherv words, a chattering or disturbance might take lplace on theline which would prevent a clean and effectual'break fromftaking place.

However, as stated above, when=the operator opens the key K2 to breakthe incoming signals, the armature of the sending relay R2 will move toits spacing contact S. The current through the winding W5 of thereceiving relay R7 will drop to Zero and hence the current through theWinding 7.2 will maintain the armature of the receiving relay R7 on itsmarking contact M irrespective of the effect of incoming signals ontheWindingWV2.

The sounder-'N21nay be locatedf at:

Current Will `thenviioW throughfground, the

resistance Z6, the Winding TV3, the contact P2, the contactP3, thereceiving relay armature,

`the marking contact `M1 andthe 4battery B3,

. Thus, it is seen that Whenthe key K1 is operated, theloop L2 and theequipment at the repeater station, including the receiving and sendingrelays R1 and R2, respectively, are interconnectedfor half-duplextelegraphy as stated hereinabove. The operator at the loop L2 maytransmit signals by operating his key K2 and pulses of alternatingcurrent will, accordingly flow over the circuit L3. l/Vhen the operatorat the loop desires to receive signals, he Will close hisY key K2 andpulses of alternating current received over the circuit L1 Will beregistered by the sounder N1 athis loop. The operator at the loop mayobtain control of the circuit extending to the distant station, Whilesignals are incoming, by opening his key K2. Irrespective -of incomingsignals, this Will cause a spacing `signal to be transmitted to thedistant station which Will interrupt the transmission of signals by theoperator at said station by connecting like batteries to both ends ofthe distant loop. No break relay is required in this half-duplextelegraph system. The features of the break relay aresupplied by thecircuits attached to the receiving and send-` ing relays R1 and R2,respectively. Moreover, the sounder N2 at the repeater station iscontinually operated and will register all signals transmitted by thelocal station.

The key K1 may be placed in its normal, unoperated position to provide afull-duplex telegraph circuit. The loop L2 Will then be the sending loopand the loop L,L the receiving loop. The key K2 at the loop L2 will bethe essential element required for the transmission of signals over theVcircuit L3 to the distant station. The sounder N3 Will be the essentialelement of the loop Lirfor receiving signals over the circuit L1 fromthe distant station. A key K3 may, if desired, be inserted in seriesWith the sounder N3 at the loop L2. Since the properties of a breakingarrangement are obviously not required in a full-duplex system, thecircuit including the Winding W3 of the receiving relay R1 is soarranged that current lows continuously through said Winding when thekey K1 is unoperated. The resultant effect ofthe Windiings W4 and W3Will then besuch as to tend to operate the armature of the receivingrelay Rl to its spacing contact S. Thus the combination oi the windings72 and W3 will serve as a biasing Winding for the receiving ture of therelay Rlthrough the contacts P3 and P3 of the key K1, and a battery B3,which may, if desired, be located at the repeater station, Will be inseries With the loop L2. `When the armature of the relay R1 closes itsmarking contact M, the batteries B3 and B3 Will `bein series with eachother and their eii'ects `Will be additive, thereby providing asubstantial current through the sounder N3 of the loop L4. This currentwill create an audible signal at the loop L2. When the armature of therelay R1 closes its spacing contact Sythe batteries B7 and B3 Will thenbecome connected in series relationship, and inasmuch as their voltagesare substantially equal and their polar-ities opposite, practically nocurrent Will i'iovv through the sounder N3 at the loop L4. Consequently,the sounder N3 will be unoperated, thus registering a sp acing signal."Thus, it Will be apparent that the sounder N3 at the receiving `loop L2will follow the signals received over `the circuit L1.

While the key K1 remains in its normal,

unoperated condition for full-duplex signaling, the battery B3 Will beconnected through contacts P3 and P3 to the apex J of the balanced` loopL2. ,A ldeiinite current will flow unidirectionally` through the WindingW3 of the relay R2 and the eii'ect of this current will tend to move thearmature of the `relay R2 to its spacing contact S. When the key K2 atthe sending loop L2 is closed, batteries "B, and B3 Willbe in seriesWith each other and their eH'ects will be additive, there,- byproducing` a dominating magnetic Veifect in the Winding TVT Which willmove the armature` of` the sending relay R2 to its marking contact M.The generator Gr` will then transmit current over the circuit L3. Whenthe key K2 at the `loop L2` is opened, no current Will floiv throughlthe Winding W7 and the magnetic effect of the Winding W3 Willdominatethe armature of the sending relay and this armature Will close itsspacing contact S. No currentivill then loivifrom thefgenerator `Gr overthe circuit L3. 2

JTWhile this invention has been shown in certainparticular arrangementsmerely for the purpose oit' illustration, it Will be understood that theprinciples of this invention may be applied to other and `vvidely variedorganizations Without departing from the spirit of the invention and thescope of the appended claims. i 2 3 y Vhat is claimed is:

1. In a telegraph system, the combination of a sending relay, areceiving relay, a loop connected to thewinding of the sending relay, akey being included in the loop, means responsive `to the opening of the`key to y lbring the armature-of said sending relay into a predeterminedposition, `means responsive to the operation of `said-sending relay tobring the armature of the receiving relay intol a: predeterminedposition and to maintain these armatures in said positions while the keyremains open, anda sounder connected in series withthe armature andoneof the contacts of the. sending relay.

2. In a telegraph system, the combination of a sending relay, a.receiving. relay, aloop yconnected to the winding of the sending relay,akey being included insaid loop, means responsive to the opening of thekey to bring the armature of the sending relay into a predeterminedposition, means to subsequently bring the armature of the receivingrelay into a predetermined:position,and tovmaintain the armatures of thesending and receiving relays in these positions while the key remainsopen, and a sounder connectedin series with the armature and one of thecontacts of the sending relay.

3. In a telegraph system. havingsending and receiving relays arrangedfor half-duplex operation, the'combination of means to produce a breaksignal, said means comprising means to bring the armatures of" thesending and receiving relays successively into predetermined positionsandv to maintain these positions forv an appreciable period of time, anda sounder controlled by the armature of the sending relay.

4. In a half-duplex telegraph system, the combination of a receivingrelay having a main winding through which pulses of direct current flowand two auxiliary windings having a common terminal, one of theterminals of one of the auxiliary windings being grounded, a.grounded-battery connected to the terminal common to said auxiliarywindings, a sending relay having a grounded armature, the contact: ofsaid sending relay being connected to the ungrounded tei-- minal oftheother ofthe auxiliary windings, a sounder, and a secondV groundedbattery connectedto the contact of the sending relay through saidsounder.

5. In a carrier telegraph system having sending and receiving relaysarranged for half-duplex operation, the-sending relay in`1 cluding anarmature and two contacts, the combination of means to produce a(clean-cut break signal, said means comprising means to bring thearmatures of the sending and receiving relays successively intopredetermined positions and to maintain these armatures in thesepositions for an appreciable period ot' time, a sounder connected inseries w-ith the armature and one of the contacts of the sending relay,and a source of alternating current connected in series with thearmature and the other of the contacts of the sending relay.

April 1931-.

WIL'ION T. REA.

6. In a half-duplex telegraph system the

